I don't think that this is an 'or' question.
Different aspects of an archival record are needed for different pruposes.
Much of this will come out when we attempt to get a more comprehensive set
of actors and use cases.

A 'nearly accurate' historical archive is valuable for historical research.
I say 'nearly accurate' to allow for the editing or deleting of silly
mistakes or embarrasing errors.

In order for collaboration to be most effective, we need to provide stable
points in the duscussion.
One of these is a summary of the various positions and ideas that have been
proposed in a given 'thread'. This just organizes the results of what is
otherwise a rambling record.
The next is the point at which decisions have finally been made and agreed
upon, possibly with dissenting views.

These stable points are necessary for collaboration in order to be able to
find and organize the set of agreements that the collaboration has produced.
Having to reconstruct them from scratch every time is energy consuming and
error prone.

At some point in the collaboration on a sizeable project, we need to
document the results in a form that others can follow for understanding the
final product. It shouldn't be necessary to wade through all of the history,
but the salient parts of the history should be available.

This is exactly what happens in the evolution of scientific or mathematical
theory. Learning calculas, for example, would be a major undertaking if all
that was available was the journals of Newton and Leibniz (if I have the
names right).

David Parnas wrote an excellent paper called "A Rational Design Process: How
and Why to Fake It", in which he says that no real project ever got built
from the top down, but that we can and should construct a paper trail that
represents how a true top down approach could have brought about the results
that actually occurred.

I think of IBIS in this way. Studies have shown the resistance that many
people have to classifying their comments as they make them. A refactoring
that creates and IBIS style discussion from a less structured discussion
could be ectremely valuable.

Neil Larson build a networkd based hierarchical, hyperlinked collaboration
system. His experience was that the system required an knowledge worker to
organize areas of high activity to provide a hypertext system that could be
navigated at any time.

The Extreme Programming Wiki found that elements needed to be refactored
when they got too disorganized. Since refactoring is one of their main
principles because they found the same necessity in code, we can either say
they wer biased toward refactoring or that their experience that it was
necessary in code is a good reason to consider that it will be necessary in
other forms of task oriented expression.